Download Slide - Woodland Park Zoo

Reptiles
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Prepared by Woodland Park Zoo Education Department
2004
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Slide 1
Woodland Park Zoo logo
Slide 2
Reptiles
Slide 3
Reptiles
What’s so special about reptiles?
•Ectothermic (cold-blooded)
•Amniotic eggs with hard or leathery shells (four membranes and shell)
•Scales (no fur or feathers)
•Offspring are replicas of parents (sexually immature)
•Mainly carnivorous
The combination of characteristics that separate reptiles from other vertebrates include
skin covered in scales (no feathers or hair and few skin glands), ectothermic body
temperature regulation (like amphibians), and amniotic eggs with leathery or hard shells.
The amniotic eggs of reptiles, with their hard or leathery shells that prevent the embryos
from drying out, permitted reptiles to make a break from water. Not only can reptiles live
on land, they can live quite independently of water. Thus, reptiles are capable of
inhabiting very arid regions where few amphibians are found. Reptiles have a wide
distribution across the globe, living on every continent except Antarctica, though they are
still limited by freezing temperatures in polar regions and on high mountains.
The scaly skin of reptiles is another feature that has allowed reptiles to live on land and
independently of water. Although the scales of reptiles appear to be little plates attached
to the skin, they are actually formed by folds and thickenings of the skin, which is a
continuous sheet. With little gas exchange taking place across their scaly skin, most
reptiles have well-developed lungs that they rely upon for breathing.
When reptiles hatch or are born, they are essentially small, sexually immature adults.
Unlike amphibians, they do not exhibit a larval stage nor go through metamorphosis.
Some reptiles continue to grow throughout their lives, though the rate of growth is often
dependent on temperature and light conditions and the availability of water and food.
The vast majority of reptiles, both as young and as adults, are carnivorous. Tuataras and
most lizards feed on a variety of invertebrates, while the larger lizards may take
vertebrates such as small mammals and birds. Some lizards, such as some species of
iguana, primarily eat plants. Snakes and crocodiles are almost exclusively carnivorous.
Crocodiles will scavenge meat from dead animals, while snakes do not commonly
scavenge but hunt their prey.
Slide 4
Amphibian and Reptile Evolution
375 mya: amphibians are the first four-legged animals on land
350 mya: reptiles emerge—the advancement of the egg!
250 mya: mass extinction—90% of all species
220 mya: surviving reptiles diversify and grow in size, dinosaurs evolve and
dominate newly emerged mammals
215 mya: flying reptiles
150 mya: birds evolve from dinosaurs
65 mya: dinosaurs extinct, mammals diversify and grow in size
Although amphibians were the first vertebrates to colonize land, reptiles, which are
descended from amphibians, adopted several physiological and behavioral adaptations,
such as their eggs, that enabled them to become fully terrestrial, reach larger sizes, and,
eventually, to become the dominate vertebrates on land for a long period of time. The
first early reptiles inhabited the earth roughly 350 million years ago. After a mass
extinction in which 90% of all species perished, surviving reptiles diversified greatly and
dinosaurs emerged, becoming the most prominent terrestrial vertebrates during the
Mesozoic Era. Recently emerged mammals were dominated by dinosaurs and remained
small in size until dinosaurs went extinct at the end of the Mesozoic era. Birds are related
to dinosaurs. The first birds coexisted with dinosaurs but birds have survived into present
times. Modern crocodilians have existed from the latter part of the Mesozoic era until the
present times and are considered to be the nearest living relatives of birds. Other reptiles
that inhabit the earth today are descended from reptile species that survived the extinction
at the end of the Mesozoic Era.
Slide 5
Reproduction and Offspring
•Shelled eggs require internal fertilization
•Most reptiles do not care for their young
•Offspring self-sufficient
As reptiles adapted to terrestrial life, the laying of shelled eggs necessitated the
development of internal fertilization. The eggs must be fertilized before the shell is laid
down, and thus, internally. This means that the eggs must be fertilized while inside the
female’s body. Fertilization is internal in all reptiles, and male reptiles, excluding
tuataras, have special organs used to accomplish this. Most reptiles mate on land, but
crocodilians and aquatic species of turtles mate in the water.
Many reptiles that lay eggs take measures that ensure proper temperatures and moisture
levels for the development of their young. However, after birth or hatching, most young
reptiles are on their own.
Slide 6
Order Testudines: Turtles and their relatives
•Shell—most have hard shells, some have soft
•Four legs—most with clawed toes
–Sea turtles have flipper-like legs to propel through water
•No teeth—strong beaks adapted for the feeding habits of each species
•Found on all continents except Antarctica
–Marine species mostly found in tropical waters of the Atlantic, Pacific, and Indian
oceans, but may range farther towards poles
It would not be difficult for most people to pick a turtle out of a crowd of reptiles. The
distinctive characteristic of species in the Testudines order, a shell, is a unique and
recognizable trait. Not all, but the majority of the approximately 300 species of
Testudines do have hard shells; some species have soft shells. Most turtles have four legs
with clawed toes, however some species have modified legs. Sea turtles rely on their
flipper-like legs to propel them through the water. Turtles do not have teeth, but their
mouths, called beaks, are strong and adapted for the feeding habits of the species. Some
turtles have beaks that are hooked, notched or serrated. Turtles and their relatives are
found on all continents except Antarctica. Marine species are mostly found in tropical
waters of the Atlantic, Pacific, and Indian oceans, but may range farther towards poles.
Slide 7
Turtle Characteristics
•Tortoises: land-dwelling turtles, primarily herbivorous, eat a wide variety of plants
•Freshwater turtles: omnivorous, eating worms, arthropods, amphibian larvae, fish
•Sea turtles: omnivorous, eating seaweed, fish, crustaceans, mollusks and jellyfish
Most reptiles are carnivorous. The prime exceptions are the tortoises, which are mainly
herbivorous but may occasionally scavenge meat from dead animals or eat fresh meat.
Freshwater turtles may eat some plant material along with their diet of small animals. Sea
turtles can be considered to be omnivorous, as they eat seaweed and other marine plants
along with jellyfish, mollusks, fish and crustaceans.
Slide 8
Order Crocodylia: Crocodiles and their relatives
•Large scales are underlain by bony plates that reinforce the scales
•Highly adapted to aquatic life—eyes, nostrils and ears on top of head
•Outer earflaps
•Crocodilians don’t have vocal cords, but use a variety of sounds to communicate
The long-snouted, well-toothed members of the order Crocodylia are an impressive group
of reptiles. In many members of this group, the large scales are underlain by bony plates
that reinforce the scales. Crocodilians are extremely aquatic and have special adaptations
for this mode of life. The eyes, nostrils, and ears are all located on the upper side of the
long head and snout so that the crocodile can remain virtually underwater but still see,
smell and hear. Crocodilians are the only reptiles that have outer ear flaps. These flaps
remain closed most of the time, though a small slit opens up when the ears are above
water, allowing crocodilians to hear airborne sounds. Crocodilians use a variety of sounds
to communicate, though they do not possess vocal cords. Crocodilians have different
calls to communicate threat, distress, hatching, and contact. Some male crocodilians
produce bellows to attract mates during courtship.
Slide 9
Crocodilian Distribution and Characteristics
Crocodiles
•most widespread: southern U.S., Mexico, Central and South America, Africa,
India, southeast Asia, and northern Australia
•pointed snout
•when mouth closed, both rows of teeth visible
•contains largest living species of reptile, the saltwater crocodile
Alligators
•two species worldwide (American and Chinese)
•when mouth closed, only top row of teeth visible
•rounded snout
Caimans
•six species, found in South America
•same family as alligators
•pointed snout
•shorter tail than alligator
Gharial
•one species, found in India
•long, slender snouts adapted for catching fish
The 23 species of living crocodilians include crocodiles, alligators and caimans, and the
gharial. Crocodiles are classified in the family Crocodylidae, which includes the largest
living species of reptile, the saltwater crocodile (Crocodylus porosus). Although some
snakes can grow longer, if you take both length and body weight into account, these
crocodiles reach the largest overall size of any living reptile. Large adult males can grow
up to 20 to 23 feet (6 to 7 meters) in length, though males over 16.5 feet (5 meters) are
rare. Large males can weigh up to 3,300 pounds (1,485 kg). Crocodiles can be
distinguished from alligators by the shape of the snout and the placement of the teeth.
Crocodiles generally have snouts that are more pointed than those of alligators, which are
usually broad and rounded. A more distinguishing characteristic is that in alligators the
upper jaw is larger than the lower jaw, such that when an alligator’s mouth is closed only
the upper teeth project and are visible. On the other hand, crocodiles’ jaws are
approximately the same size, so when the mouth is closed the teeth interlock and both the
upper and lower teeth are visible along the outer edges of the jaw. The fourth tooth is
particularly prominent in crocodiles and is easily seen projecting upward from the lower
jaw.
Crocodiles are the most widespread of the crocodilians. Species of crocodiles are found
in the southern United States, Central and South America, Africa, India, southeast Asia,
and northern Australia. There are only two species of alligator worldwide: the American
alligator (Alligator mississippiensis) in the southeastern United States, and the Chinese
alligator (Alligator sinensis) in the Yangtze River basin of China. Caimans are grouped in
the same family with alligators and these two types of crocodilians are very similar in
many ways. Caimans are mainly found in South America. Caimans and alligators can be
visually distinguished by their heads and tails. Alligators generally have broader, more
rounded snouts and caimans have more pointed snouts. Caimans tails’ are usually shorter
than alligators’ tails.
The last group of crocodilians includes only one species, the Indian gharial (Gavialis
gangeticus), which is found mainly in rivers of India but extends into river systems of
surrounding countries. Gharials have long, slender snouts that are adapted for catching
fish, their main prey.
Slide 10
(photos of caiman, gharial, American alligator and West African dwarf crocodile)
Slide 11
Order Rhynchocephalia: Tuatara
•Similar in outer appearance to lizards, differ in fertilization
–tuataras: contact of the cloacas of the male and female
–other reptiles: males possess organs that are inserted for internal fertilization
•Found on islands off New Zealand
•Two species
–one discovered in last 10 years
•Behavior:
–nocturnal
–burrowing
–carnivorous
–low reproductive rate
The order Rhynchocephalia contains only two species, both in the genus Sphenodon.
These two species of tuatara are found only on small islands off the two main islands of
New Zealand. Tuataras were once found throughout New Zealand, but introduced rats,
which prey on the eggs and young of tuataras, have affected their populations. Tuataras
are similar in outward appearance to lizards. Tuataras differ from all other reptiles in that
internal fertilization is accomplished through contact of the cloacas of the male and
female; in other reptiles, the males possess organs that are inserted for internal
fertilization.
Tuataras are burrowers and are active nocturnally. They are mainly carnivorous and eat
such animals as worms, insects, lizards, millipedes and even small seabirds. Tuataras do
not reach sexually maturity until sometime between the 10th and 20th year of life,
depending on climatic conditions and food availability. Once they begin reproducing,
female tuataras only lay one clutch of eggs, usually around a dozen, every four years.
Tuataras are long-lived and do not even reach full adult size until around 60 years of age.
Slide 12
Order Squamata: Lizards, Snakes and Amphisbaenians
•Largest order of reptiles
•Three distinct suborders:
–Sauria (lizards)
–Serpentes (snakes)
–Amphisbaenia (amphisbaenians or worm-lizards)
•Paired male organs used to accomplish internal fertilization
–Hemipenes differ from the single organs of turtles and crocodiles, tuataras lack
such organs
•In most lizards and snakes, the scales of skin overlap one another, providing extra
protection and reducing the loss of moisture
The order Squamata is the largest order of reptiles and contains, according to many
taxonomists, three suborders that are rather distinct from one another: Sauria (lizards),
Serpentes (snakes), and Amphisbaenia (amphisbaenians or worm-lizards). One
characteristic of this group is the paired male organs used to accomplish internal
fertilization. These hemipenes differ from the single organs of turtles and crocodiles,
while the tuataras lack such organs. In most lizards and snakes, the scales of the skin
overlap one another, providing extra protection and reducing the loss of moisture.
Slide 13
Lizards
•Two pairs of clawed limbs
–except legless lizards
•Some lizards have moveable eyelids with a third membrane
•External ear openings
•Some species can lose and regenerate parts of their tails
•Size:1.4 inches to 10 feet (gecko to Komodo)
•Two venomous species
–gila monster
–Mexican beaded lizard
•Mainly carnivorous
–primary food insects
–some herbivores (iguanas)
–some feed on larger prey (Komodos)
Several physical characteristics separate lizards from snakes and amphisbaenians,
including two pairs of limbs, sharp claws on the fingers and toes and external ear
openings. Some lizards, but no snakes or amphisbaenians, have moveable eyelids with a
third membrane, called a nictitating membrane, that sweeps across the eye surface and
keeps it clear of debris. In several families of lizards, some species have reduced limbs or
no limbs at all. These legless lizards, however, retain the other physical characteristics
specific to lizards. The amphisbaenians have physical characteristics different enough
from lizards and snakes to be considered in their own group.
Many lizards can shed the latter portion of their tails, which may occur if the lizard is
being attacked by a predator. When the tail separates, muscles in the remaining part of
the tail contract to prevent the loss of blood and, eventually, a new tail regenerates.
Snakes do not possess the ability to shed and regenerate their tails. Lizards range in size
from a small gecko at 1.4 inches (3.5 cm) long to 10 feet (3 m) long and can weigh up to
300 pounds (135 kg), the largest being male Komodo dragons, a species of monitor
lizard.
Only two species of lizards are known to be venomous: the Gila monster (Heloderma
suspectum) and the Mexican beaded lizard (Heloderma horridum). The venom of these
lizards could be fatal to humans but only small amounts are usually released, so bites
from these lizards are not normally deadly. These species do not have hollow fangs, like
some snakes, but have grooved teeth that direct the venom from where it is released by
the venom gland into the bite wound. In order to direct enough venom into the wound,
these lizards usually bite their prey repeatedly in the same spot using a chewing motion.
The venom can immobilize and partially predigest prey.
Lizards feed on invertebrates of many different types, though larger species may prey on
vertebrates, and most species are not highly selective in their choice of prey. There are
some species of lizards that are quite large, particularly Komodo dragons, which are
capable of catching and eating large animals such as small deer and pigs. Some lizards,
particularly iguanas, are herbivorous.
Slide 14
Snakes
•Legless
•Lack bladders
•Eyelid scales, called brilles, fused together to form transparent / protective shield
•Both halves of their lower jaws are able to move independently of one another
•Do not have external ear openings; “hear” using vibrations
•Snakes range in size from 5 inches (slender blind snake) to 30 feet (green anaconda
and reticulated python)
Snakes are recognized as reptiles that do not have legs. There are, however, several other
characteristics used by scientists to set snakes apart from other reptiles. Snakes do not
have external ear openings or bladders and both halves of their lower jaws are able to
move independently of one another; they are not fused together as in lizards. In snakes,
the eyelid scales, called brilles, are fused together over the eye but are transparent,
creating a permanent protective shield over the eye. This shield may be scratched, but is
shed periodically along with the skin, so any damage is only temporary. It is this
combination of characteristics that makes a snake a snake; there are other reptiles in the
order Squamata that do not have legs but that do not possess other characteristics of
snakes and are thus classified in their respective suborders. Although a snake might look
like one long tail, the head and body are usually the longest part of a snake. The body
ends and the tail begins at the cloacal opening of the snake.
The longest snakes in the world are the green anaconda (Eunectes murinus) of South
America and the reticulated python (Python reticulatus) of southeast Asia. Both of these
snakes can grow up to 20 feet (6 m) with some individuals reaching 30 feet (9 m). The
smallest snakes are the thread snakes, also called slender blind snakes, the smallest of
which grow to about 5 inches (13 cm) long and are very thin.
Slide 15
Amphisbaenians (worm-lizards)
•Closely related to lizards and snakes
•Legless (with the exception of a few species which posses front legs
•Adopted a burrowing lifestyle
•Poorly developed eyes with transparent, fused eyelids protecting the eyeballs
•Range in length from approximately 3 inches (8 cm) to 2.6 feet (80 cm)
•Eat mostly insects and other invertebrates.
The amphisbaenians, or worm-lizards, are closely related to both lizards and snakes.
These species lack limbs and have adopted a burrowing lifestyle. Because of this
secretive lifestyle, less is known about amphisbaenians than lizards and snakes and they
are unfamiliar to many people. The heads of amphisbaenians are well adapted for
burrowing and, due to their reliance on other senses, amphisbaenians have poorly
developed eyes with transparent, fused eyelids protecting the eyeballs. Amphisbaenians
range in length from approximately 3 inches (8 cm) to 2.6 feet (80 cm).
Amphisbaenians, which are found in Africa, southern parts of North America (south from
California and Florida), Central and South America, western Europe (Portugal and
Spain), and in the Middle East, eat mostly insects and other invertebrates.
Slide 16
Importance of Reptiles and Amphibians
•Cultural icons
•Maintain balance of nature
–prey
–predator
–scavengers
Humans have differing attitudes towards reptiles and amphibians, as we do towards other
aspects of the natural world. Reptiles and amphibians have appeared as revered cultural
icons throughout history. The Huron of mid-eastern Canada (a confederation of four
tribes with a common language called Wyandot) included a toad and a tortoise as key
figures in their creation myth. The story goes that, in the beginning, the world was made
of water. A divine woman fell from the sky and was caught by loons. The loons tired of
carrying her, so she needed earth upon which to stand. Several animals attempted to dive
to the bottom of the water and bring up earth, but they failed. Only the toad succeeded in
returning with some earth.
On searching [the toad’s] mouth, the tortoise found in it some
earth, which he gave to the woman. She took it and placed it
carefully around the edge of the tortoise’s shell. When thus placed,
it became the beginning of dry land. The land grew and extended
on every side, forming at last a great country fit for vegetation. All
was sustained by the tortoise, which still supports the earth.
This myth is only one of many examples of how reptiles and amphibians have been
important figures in human culture. On the other hand, some people associate reptiles and
amphibians with danger and disgust. It is true that some reptiles, and some amphibians,
can be very dangerous to humans. The vast majority, however, are not dangerous. As we
expand our knowledge of reptiles and amphibians, we can better understand the ways in
which these animals have adapted to survive and appreciate their important roles in the
world’s ecosystems, and thus let go of some of those negative feelings.
Many reptiles, especially snakes, eat diets that consist largely of small mammals, such as
rodents. In this way, reptiles play an important role in maintaining the natural balance of
species in an environment. This can be especially helpful to farmers because rodents, if
their populations get out of balance, can damage crops and consume stored grain.
Similarly, the majority of amphibians, and many lizards, prey on invertebrates, such as
insects, and help to control their population numbers. In turn, amphibians provide a high
protein food source for animals such as snakes, birds and some mammals. Many of these
larger animals do not themselves feed on invertebrates, and thus the amphibians serve as
a necessary step in the transfer of energy up the food chain. In addition to being
predators, Komodo dragons are also scavengers. Scavengers are nature’s cleanup crews.
They eat dead animals that would otherwise rot and spread diseases to other animals.
Slide 17
Threats to Survival
•Habitat Loss
•Introduced Species
–endangered pygmy blue-tongue lizard
–brown tree snake, threat to birds
•Pollution
–alligator eggs in Florida
–sea turtles and plastic bags
•Pet/Product Trade
–Egyptian tortoise driven to extinction in its native range due to collection for pet
trade
Although reptiles have existed on earth for millions of years, there are current factors
threatening the survival of many species of these animals. For the most part, these threats
are caused to varying degrees by human impacts on the earth’s ecosystems. Today’s
extinctions are occurring at an unprecedented rate over a much shorter period of time
than other known extinctions in earth’s history. Many human activities have impacted the
environment; these activities can collectively have consequences for living things around
us. It is generally agreed by conservation scientists that the four major current threats to
the survival of animals and plants as we know them are, in order of severity, habitat
destruction, introduced species, pollution and overexploitation (e.g. hunting, collecting).
These threats are all compounded by the currently rapid rate of human population growth.
HABITAT DESTRUCTION
As human demands on resources increase, and as human populations grow, our pressures
on the land also increase. Land may be turned over to agriculture or human habitation,
mined, logged, or otherwise altered in ways that make the land useful for humans but
may not allow for the survival of all the species that once lived there. In cases where the
value of the land as habitat for animals and plants is significantly decreased, these
changes are referred to as habitat destruction. When habitat is destroyed, living organisms
are deprived of some or all of their basic needs for survival: food, water, air, shelter and
space.
INTRODUCED SPECIES
The second major impact on the survival of species are the effects, direct and indirect, of
introduced species. Introduced species are species of plants and animals that have been
transplanted from their native habitats to new habitats. This transplanting, whether it
occurs accidentally or on purpose, is mainly due to human activities.
There are many examples of reptiles that have been threatened by introduced species.
Often, once introduced species have established themselves, it is very difficult to right the
situation. All over the world, habitats are currently under the influence of numerous
introduced species. In Australia, the pygmy blue-tongue lizard was once thought to have
disappeared altogether, but a small breeding population was rediscovered in the early
1990s. Although this species was rediscovered, there is no doubt that it has suffered from
the influence of introduced species, in this case plants. The habitat of this lizard in South
Australia has been affected by grazing and introduced pasture grasses have come to
dominate the vegetation along the banks of the streams. Very little of the native
vegetation community upon which this lizard depends remains, and where it does, it
occurs in fragmented patches.
There are also many examples of reptiles that have been introduced to different parts of
the world and have had negative effects. A good (or bad) example is the brown tree
snake, which was accidentally introduced from its native range of northern Australia,
Indonesia, New Guinea and Solomon Islands to the island of Guam after World War II.
The brown tree snake, an adept predator of birds and their eggs, has caused the drastic
decline of nine of the 12 species of birds native to Guam. Now dense on Guam, up to
12,000 snakes per square mile in some areas, scientists are concerned about the further
spread of the snake, especially to other islands such as the Hawaiian Islands, which are
home to 41 percent of all endangered birds in the United States. The brown tree snake has
already been intercepted at least six times in association with aircraft coming from Guam
to Hawaii, but has not yet established itself on the Hawaiian Islands. It is hoped that it
never will, or Hawaii’s native bird life may become even more endangered.
POLLUTION
Over the years, the creation and disposal of poisonous chemicals and other environmental
toxins has polluted all of earth’s ecosystems to varying degrees. Pollution can affect
species in many ways. Certain chemicals disrupt the hormone levels in some animals,
resulting in abnormal reproductive systems or developmental processes. In Florida,
alligator eggs were examined for effects of chemicals found in high levels in certain
lakes. The affected young alligators were found to have abnormal internal and external
reproductive organs and skewed hormone levels. Garbage, especially plastics, that is
discarded carelessly can be harmful to many species of reptiles. For example, sea turtles
sometimes mistake floating plastic bags for jellyfish and eat them. This can cause the
turtles to become sick and even die.
PET/ PRODUCT TRADE
The demand for live reptiles to be kept as pets, as well as for products produced from
their bodies, is a modern threat facing these species. Populations faced by other threats,
such as those described in the previous paragraphs, can be put over the edge by the
impact of harvesting for the pet or product trade.
Reptiles are popular as pets, especially in classrooms. Some species, such as leopard
geckos, corn snakes, boa constrictors and bearded dragons, which are bred very
successfully in captivity, are relatively easily cared for and can be handled. Other species,
however, are difficult to breed in captivity and thus, many animals that are available for
purchase are taken from the wild. There are many cases where species of reptiles have
become endangered due to collection for the pet trade. In Egypt, the Egyptian tortoise
was driven to extinction in its native range within a matter of years due to rapid collection
for the pet trade. Egyptian tortoises are now found in the wild only in national parks in
Israel. On a local level, it is important that native reptiles be left in the wild and not
removed to become classroom or house pets. These species may be difficult to care for,
or those who capture them may not have proper care information, and most do not
survive for long out of their wild habitats. Collecting native species from the wild only
puts more pressure on populations already facing habitat destruction, pollution and other
threats to their survival.
Another problem related to reptiles in the pet trade is that of exotic species being released
into local habitats. As explained in previous sections, if these introduced species are able
to survive where they are released, they can alter the native habitat and impact native
species. Furthermore, releasing exotic pets, or even dumping water from tanks that have
housed exotic species, can introduce diseases into local habitats. Native species may have
few defenses against these diseases and can be impacted significantly. It is important that
pet reptiles are taken care of properly and not released into the wild. In making a decision
to keep reptiles as pets, it is important to understand the care and responsibility involved
in keeping the pet healthy, as well as the life expectancy of the pet so as to understand the
duration of your commitment.
Slide 18
Washington Species
Washington state encompasses a diversity of habitats and thus, a rich biodiversity of
plants and animals. The region west of the Cascades crest, where the land is mainly
cloaked in temperate forests, receives a significant amount of precipitation each year. The
Olympic and Cascade mountain ranges together create a barrier to moist air as it travels
inland from west to east. Thus, the eastern portion of Washington state is significantly
drier in the Columbia Basin region. Due to these climatic conditions and the adaptations
of reptiles and amphibians, there are more species of reptiles inhabiting eastern
Washington than there are western Washington, but the opposite is true of amphibians,
with more species of amphibians, particularly salamanders, inhabiting the wetter west
side.
Garter snakes are found west of the Cascades. The common garter is found all over the
state. It’s primarily aquatic and eats fish, frogs, tadpoles and other aquatic animals.
Northwestern garter snakes are not found east of the Cascades and are extremely varied
in coloration and pattern. The Great Basin rattlesnake inhabits arid to semi-arid, rocky
areas up to 7,000 feet. It’s mild-tempered compared to other rattlesnakes and eats small
mammals, birds, lizards and frogs. The rubber boa occurs throughout much of
Washington, in many different habitats. They have a short, blunt tail that resembles the
head. Because of this, rubber boas are also called two-headed snakes.
Slide 19
More Washington Species
Side-blotched lizards are found in eastern Washington in a variety of habitats and usually
stalk their prey, which includes insects and other small arthropods. The short-horned
lizard is also found in eastern Washington and feeds primarily on ants. The northern
alligator lizard is found all over western Washington and some parts of northeast
Washington. The southern alligator lizard inhabits central Washington. The northern and
the southern alligator lizards are different from all other lizards in that they have a lateral
fold on each side of their trunk. The western skink is found all over eastern Washington.
It has a bright blue tail and feeds on small invertebrates.
Slide 20
Western Pond Turtle
•Pacific Northwest native
•Population drastically reduced due to habitat loss, introduced species, disease and
pollution
•Western Pond Turtle Project
-Newly hatched turtles “head-started” at Woodland Park Zoo
-Released into wild when large enough
Western pond turtles have lived in slow backwaters of rivers, ponds, lakes and marshes of
the Pacific Northwest region for thousands of years. However, by the mid-1980s, the
western pond turtle population in Washington had been drastically reduced. In 1993, the
western pond turtle was listed as endangered by the Washington Department of Fish and
Wildlife (WDFW). This species is also listed as a species of concern under the
Endangered Species Act (ESA) of the United States Fish and Wildlife Service (USFWS).
What happened to Washington’s native pond turtles? Several factors have come into play
over the history of western pond turtles. Humans have long considered wetlands to be
land of little value. For this reason, more often than not, wetlands have been drained or
filled so that the land could be paved over and developed. These actions significantly
reduced the healthy habitat available for animals such as pond turtles. Western pond
turtles have also suffered from the introduction of bullfrogs (Rana catesbeiana) and
largemouth bass (Micropterus salmoides) into the region. Bullfrogs were introduced to
the western United States from the eastern United States in the early 1900s. Bullfrog legs
were sought after for food and the introduced bullfrogs were hunted as game. Bullfrogs
are large (adult males can be longer than 7 inches [17.5 cm]) and eat a variety of animals
from small insects to birds as large as robins. Predation by bullfrogs and largemouth bass
has had a significant effect on the survival of baby pond turtles. Other factors affecting
pond turtle populations include disease and environmental pollution, such as oil spills.
Since the start of the Western Pond Turtle Project, biologists from Woodland Park Zoo
and the WDFW have been working to protect baby western pond turtles from introduced
predators and to increase the size of the pond turtle population. This has been
accomplished by taking newly hatched pond turtles from the wild and raising them in
captivity for a year before releasing them back into the wild, thus giving them a “headstart” on life. Once a female has finished laying her eggs, biologists cover the nest with
wire mesh “exclosures” to protect the eggs from predators such as raccoons and skunks.
After approximately 100 days of incubation, the eggs hatch and the hatchling turtles are
collected and brought to an off-view holding area at Woodland Park Zoo for the head-start
program. After a year of growth, the pond turtles are large enough to avoid being eaten by
bullfrogs and largemouth bass.
At the beginning of the head-start program, field evaluations were conducted to assess the
progress of turtles that had been through the program and it was determined that this was
the best course of action for restoring the species to Washington state. Biologists also
work to control the population of bullfrogs. One way they accomplish this is by removing
bullfrog egg masses (which may contain over 10,000 eggs) from the ponds where pond
turtles are released. The Western Pond Turtle Project has also involved captive breeding
of the few wild turtles found in the Puget Sound area. These turtles, which are housed and
bred at Woodland Park Zoo, represent some of the last individuals of a former western
Washington population and will be the foundation for any new populations established in
western Washington.
As we examine the case of the western pond turtle, it is not difficult to see that the factors
that caused western pond turtles to become endangered have also caused many other
species worldwide to face extinction. As described previously, major factors affecting the
continued survival of species, such as western pond turtles, are habitat loss, introduced
species, pollution, hunting and harvesting, all of which are directly related to human
activity and human population growth. For most species, a combination of factors has
resulted in declining populations. But as we become more aware of these common
factors, we can make efforts in our own lives to have as little impact as possible.
Slide 21
Western Pond Turtle
(photos of hatchlings, adult with radio transmitter on its back, juveniles waiting to be
released)
Slide 22
WPZ photos:
(All WPZ photos property of Woodland Park Zoo. All rights reserved.)
·Cuban anole, soft shell turtle, caiman (full body), American alligator (juvenile and
adult), desert tortoise, short-horned lizard, alligator lizard—Katie Remine, WPZ
·Indian star tortoise, yellow-spotted side-necked turtle, snake close-up, iguana, gila
monsters, Komodo dragon—Margaret White, WPZ
·Crocodile—Jenny Mears, WPZ
·Emerald tree boa, Indian python—Dennis Conner, WPZ
·Standings day gecko, baby Egyptian tortoise, caiman (head), West African dwarf
crocodile, adult Egyptian tortoise, Dale Unruh, WPZ
·Eyelash viper—Keith Neitman, WPZ
·Western pond turtle (in hand)—Fred Housel, WPZ
·Western pond turtle (on floor)—Wendy Hochnadel, WPZ
·All other western pond turtle photos—Kate Slavens, WPZ
All other photos:
(Used with permission. All rights reserved.)
·Turtle reproduction, green sea turtle, Washington native snakes, side-blotched
lizard and western skink photos by Dennis Desmond.
·Gharial, taken from public domain, wikipedia.org
·Tuatara, taken from public domain, wikipedia.org
·Amphisbaenian photo by Jakob Hallerman.
Slide 23
The End